Rheostat



T. RHODUS April 14, 1931.

RHEOSTAT Filed July 13, 1928 -/NVENTOF?:

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preferre Patented Apr. 14, 1931 UNITED- STATES THOMAS RHODUS, OF CHICAGO, ILLINOIS RHEOSTAT Application filed July 13, 1928. Serial 1T0. 292,365.

This invention relates to that type of rheostats in which an annular core affords a support for a spiral winding of resistance wire to constitute one unit of the rheostat, the

companion unit usually the adjustable one,

having movable electrical contact with the resistance windings of the first mentioned unit. .And the present improvement has for its various objects I To provide a structural formation and combination of parts (1) whereby the adjoining ends of a split ring supporting core carrying the resistance windings are coupledtogether in a secure and effectlve manner;

and (2) which in addition provides for the convenient, efiicient and substantial support of an insulating nature for the respective terminal posts of the rheostat with a minimum loss of winding space; and (3) a like insulated support for the bracket member which has attaching means and carries the adjustable" unit of the rheostat.

To provide a structural formation and association of parts in the adjustable unit of the rheostat in which, with a minimum diameter of the circular resistance carrying unit, a maximum diameter of the contact roller of the companion unit of the rheostat is attained in a simple and efiective manner.

To provide a simple and effective means for securing the carrying shaft of the ad- 'ustable unit of the rheos'tat in its supporting racket in a readily detachable manner; all as will hereinafter more fully appear.

Inthe accompanying drawing:

Fig. 1 is a plan view, partly in section on line 1-1 Fig. 2, of a rheostat embodying the d form of the invention.

Fig. 2 is a central sectional elevation on line 22,Fig. 1.

Fig. 3. is a detail horizontal section on line 3-3, Fig. 2.

Fig. 4 is a detail elevation of the inset ends of the core band.

Fig. 5 is a detail of one of the connecting plates for the aforesaid core band.

Like reference numerals indicate like partsin the several views. The resistance unit of the rheostat structure shown, oomprisesasenes of windings l of resistance wire of a spaced and flattened spiral form resulting from the winding of the wire upon a supporting core, preferably composed of a sphtring shaped band 2 of metal encased in a covering 2 of asbestos or like material.

A material part of the present invention involves means for securing the adjoining ends of the split ring shaped band 2 together in an effective and durable manner, and to such end comprises a construction and combination of parts preferably as follows:

Each end of the band 2 is formed with an outstanding prong 3 which is preferably of the flat and integral'form shown, and formed -by slitting the material of the band to form a tongue and then bending the tongue outward to constitute 2. prong 3. Each end of of the curved hand is bent inwardly and straightened and in addition is formed with a recess 4 and an orifice 5, both of a size sufiiciently large to avoid conducting contact of the metal of the band 2 with the hereinafter described terminal screw bolts by which the band 2 and associated parts are connected together in assembled relation.

In connection with the described formation of the ends of the ring band 2 aforesaid, outer and inner connecting plates 6 and 7, of asbestos board or like insulating material are arranged to fit the straight flat ends of the band and to span the split of the ring 2, with one or both plates formed with orifices 6 adapted to receive and snugly fit the prongs 3 of the core band 2, to maintaih the band 2 and also the ends of said band in proper working relation.

In addition the connecting plates 6, 7, are formed with orifices 7 in aligned relation with the recess 4 and orificesfi of the band -2, and are-of a diameter corresponding with that of the attaching screw bolts above referred to, so that there will be little if any play between the plates and the bolts. The described construction is intended to prevent any slip between the arts which would bring the terminal screw lts above referred to into electrical contact with the metal of the band 2. In such construction the screw bolts 8 being the bolts above referred to, constitute the respective terminal posts of the rheost at bracket 9 of the companion adjustable unit hereinafter described, and to such endthe depending flange 9' of said bracket lays preferably against the outer connecting plate 6 and is formed with an orifice for the passage of the uppermost screw bolt 8 of the structure, so .as to be firmly clamped in place by the attaching nut of said bolt. In the construction shown the respective connecting plates 6 and 7, extend a distance above the ring band 2 and have abutment against the under face of the main or horizontal rail of the bracket 9, with a view to prevent any lateral play of the bracket 9, with relation to the other parts of the appliance, and also.

to prevent any short circuiting connection between said bracket and the metal ring band 2. The adjustable unit of the rheostat is revolubly mounted on the supporting bracket 9 above described, and to such end the main rail of said bracket extends in to the center of rotation of the adjustable unit and is provided with a journal hub 10 for the shaft 11 of the adjustable unit which in addi tion comprises'parts as follows:

A rectangular yoke 12 has 'fixed attachment to the inner end of the carrying shaft 11, and in eccentric relation to said shaft in order that one end of the yoke will have nearer relation to said shaft than its other end, with a view to the use of the hereinafter described contact roller 13, with the same having a maximum diameter with relation to a minimum of the rheostat structure as a whole.

The end flanges 12' of the yoke 12 are formed with guide orifices for a sliding bar I l-adapted to move radially with relation to the central axis of the rheostat, and with said sliding bar having a normal outward nearest to tendency under the influence of a spring 15 associated with the bar 14 and yoke 12, as shown and as fully described in my former Patent -No.. 1,230,221 015 June 19, 1917, and the contact roller 13 above referred to is revolubly mounted at the outermost end of the sliding bar 14 in any usual manner, preferably in the manner described in my aforesaid patent; and in order to provide for the above referred to maximum diameter of the contact roller 13, the said roller 13is positioned between the windings 1 of the annular resistance unit and the short end of the yoke 12, being the end carrying the flange 12' a radio receiving or like apparatus and to such end is provided with a pair of attaching orifices 16 preferably screw threaded, for the reception of theattaching screws used.

With such arrangement the outerend of the carrying shaft 11 passes outthrough an orifice on said dial plate or panel for operative association with a handle and a suitable pointer and dial for affording an accurate indication of the amount of resistance existing in the circuit.

The yoke 12 aforesaid has bearing against ing core for a resistance winding, said core comprising a metal band, a plurality of positioning prongs on said band, a connecting plate of insulating material provided with orifices for vreceiving said prongs, a bracket member of an angle-plate form providing a support for the adjustable unit of the rheostat, said bracket member having a depending portion fitting against the edge of said connecting plate of insulating material, a terminal bolt passing through said connecting plate and said bracket member, and means securing said parts in assembled relation.

2. Inv a rheostat, the combination of a resistance member having a flat curved band, a plurality of terminals arranged in a direction across the width of said band, an adjustable current carrying contact member making contact upon said resistance member and means connecting and holding said parts in operative relation. l

In .testimony whereof I hereunto aflix my the carrying-shaft 11 above dey scribed. In the construction-shown, the main rail of-the bracket 9 is adapted to be secured to "the'inner face of thedial plate or panel of I 

